How do you weigh ancient-alien claims against the possibility of life elsewhere?

I’d separate those into two questions. Life elsewhere could be possible without there being evidence that anyone visited Earth, much less influenced human societies. One idea doesn’t prove the other.

For an ancient-visitor claim, I’d look for specific, independently checkable evidence that fits the claim better than ordinary explanations. Gaps in our knowledge can be a reason to keep asking questions, but they aren’t evidence for a particular answer.

Being open to the possibility of extraterrestrial life is reasonable. We haven’t explored most of the universe, and even the search for life closer to home is unfinished. But “we don’t know yet” cuts both ways. It leaves room for possibilities, not a free pass for any explanation.

I’d want claims about ancient contact to make clear predictions and show evidence that can be examined independently. If the argument is mostly that an old achievement seems too impressive for its time, that’s not enough by itself to establish outside help.

Maybe keep the wonder and the conclusion separate. The universe could contain life, and humans can still have made remarkable things without visitors. Those aren’t opposing positions.

I’d start by asking what the claim actually explains, then compare it with explanations grounded in the available evidence. If new evidence turns up, the conclusion can change. Until then, possibility is a starting point, not a verdict.