For those who do not know, the William Lane Craig standard Kalam cosmological argument runs as follows:

P1. Whatever begins to exist has a cause.
P2. The universe began to exist.
C1. Therefore, the universe has a cause.
P3. If the universe has a cause, then an uncaused, personal Creator of the universe exists, who sans the universe is beginningless, changeless, immaterial, timeless, spaceless, and enormously powerful.
C2. Therefore, an uncaused, personal Creator of the universe exists, who sans the universe is beginningless, changeless, immaterial, timeless, spaceless, and enormously powerful.

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Objections:

1> There is no good scientific reason for concluding our Lorentzian four-dimensional spatio-temporal manifold had an absolute beginning. Of course, we can debate Big Bang cosmology, singularity theorems (like the BGV and Hawking-Penrose theorems) and the 2nd law of thermodynamics. I have read extensively about these subjects and asked about them to several professional cosmologists (including Vilenkin, Andrei Linde and many others).

2> The philosophical arguments against an infinite regress of past events (viz., the traversal of an infinite timeline) as well as arguments against an actual infinite are fallacious and consequently unsound. Many philosophers agree on this point (e.g., Oppy, Arnold, Moriston and many others). We can debate that as well.

3> Even if it had a beginning, there is no reason to conclude it had a cause, as causality seems to be a property of the physical manifold -- if there is no manifold, there is no causality. So, Craig has the burden to demonstrate causality is transcendental (and metaphysically necessary) rather than a description of how the manifold works (and thus dependent on the manifold).

4> Even if causality holds without our Lorentzian manifold, it is a non-sequitur to say the cause must be immaterial, non-spatial and personal. This apologetical claim assumes all of physical reality began, and there is no proof this is true!

5> Even if it is shown that the cause is immaterial, it doesn't follow it must be a personal mind. Beyond the fact that many philosophers (e.g., Alexander Pruss) argue abstract objects are causally efficacious, there are other equally speculative proposals that postulate immaterial substances. Just one example: Life is defined by Qi even though it is impossible to grasp, measure, quantify, see or isolate. Immaterial yet essential, the material world is formed by it. An invisible force known only by its effects, Qi is recognized indirectly by what it fosters, generates and protects... Qi is an invisible substance, as well as an immaterial force that manifests as movement and activity. (Between Heaven and Earth, pp. 30, 34, by Beinfield and Korngold)

6> Even if I grant an uncaused sentient being, that wouldn't demonstrate it is still around today. Couldn't it have simply started everything and then extinguished itself? As philosopher Paul Edwards explained: Nor does the [Kalam] argument establish the present existence of the first cause. It does not prove this, since experience clearly shows that an effect may exist long after its cause has been destroyed. Critiques of God (p.46)

The Kalam’s problem is that you cannot prove that an infinite regress of events is impossible, (accidentally ordered series of causes). Aquinas provides a better argument in which an infinite regress of entities is impossible. It’s called an essentially ordered series of causes, in which you cannot have one cause existing without the simultaneous existence of its own cause. It has to do with movement (not just strictly locomotion but rather the change of states of being).

With this infinite regress, nothing at all would be changing because there’s actually nothing to provide any change of state, it’ll just never exist. So when we observe one thing moving or changing, we know that there is at least one end point when looked at regressively, simultaneously existing while said observed thing is changing. That is what theists call God, and that type of infinite regress is impossible

Near1:
The Kalam’s problem is that you cannot prove that an infinite regress of events is impossible, (accidentally ordered series of causes). Aquinas provides a better argument in which an infinite regress of entities is impossible. It’s called an essentially ordered series of causes, in which you cannot have one cause existing without the simultaneous existence of its own cause. It has to do with movement (not just strictly locomotion but rather the change of states of being).

With this infinite regress, nothing at all would be changing because there’s actually nothing to provide any change of state, it’ll just never exist. So when we observe one thing moving or changing, we know that there is at least one end point when looked at regressively, simultaneously existing while said observed thing is changing. That is what theists call God, and that type of infinite regress is impossible

As you said, a per se chain refers to the concurrent/simultaneous actualization of change. This kind of finitude is perfectly consistent with a past-eternal universe.

I'm inclined to agree that a per se chain can't be infinite and must, therefore, end somewhere. However, I disagree that this is what "theists call God." It could be the universe itself. How so? First, if existential inertia (not to be confused with Newton's inertia) is true of the actual world, then the argument has no force whatsoever (See Existential inertia and the Aristotelian proof). So, Thomists have to refute this possibility. Second, there are alternative accounts of per se chains (i.e., alternative to Aquinas') in which Aquinas' argument does not work:

“The account runs as follows: A per se, sustaining cause C is required for substance S’s being in condition or outcome O only if (i) there is some causal or explanatory factor or force F—intrinsic or extrinsic to S —acting on S to bring S toward some condition or outcome ~ O; (ii) F is a net factor or force in the absence of C’s causal operation; and (iii) S (or some state of affairs involving S) is in condition or outcome O distinct from ~ O. ... The account... provides a foundation for a new undercutting defeater of the Aristotelian proof." (Stage One of the Aristotelian Proof: A Critical Appraisal, p.6)
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For this reason and many others, I reject Aquinas' first way.