But that was not the question proposed -- Is God as the ultimate source and sustainer of life. The question asked was not broad but specific: Do theistic evolutionists hold that every human being -- from Adam to the present -- required a supernatural act to come into existence?
? No violations of natural laws are required, constant or otherwise, to answer the question.
If by “supernatural act” you mean God’s continual creative and sustaining causation, then yes, every human existence depends on God in that sense, and this is affirmed by all Christian frameworks, not uniquely by theistic evolution.
If, however, you mean a discrete, individual divine intervention distinguishable from ordinary biological causation, then theistic evolution does not require that assumption, nor is it required by classical Christian theology.
Without clarifying which of these you mean, the question cannot be answered in a non-trivial way.
I'll give a couple examples to help distinguish these topics:
Exodus 14:21-22
“Then Moses stretched out his hand over the sea, and the LORD drove the sea back by a strong east wind all night and made the sea dry land, and the waters were divided. And the people of Israel went into the midst of the sea on dry ground, the waters being a wall to them on their right hand and on their left.”
The splitting of the red sea would be a form of an intervention/miracle.
Colossians 1:16-17
“For by him all things were created, in heaven and on earth, visible and invisible… all things were created through him and for him. And he is before all things, and in him all things hold together.”
Or
Colossians 1:17
“He is before all things, and in him all things hold together.”
Or
Job 38:33
“Do you know the ordinances of the heavens? Can you establish their rule on the earth?”
These would be example of passages that reflect divine acts of sustainance. Holding things together. Establishing the rule of the heavens.
Intervention and divine sustaining are both supernatural in source, but they are not the same kind of act. Divine sustaining operates through natural causes and applies universally; intervention interrupts or exceeds them and is exceptional. Regarding your question, if every human being requires a supernatural act, if you mean the former, all Christian frameworks affirm it. If you mean the latter, theistic evolution does not require it.