Not at all. There are a lot of megalithic structures that could not be built today, so how do you explain that?
Civilization was either more advanced than we give it credit for or aliens came and helped.
Which do you think is more likely?
The megalithic structures that we know of are quite late vis-a-vis the post-Younger Dryas event. The pyramid of Saqqara (for instance, being the oldest Egyptian pyramid) is @4500 years old, not 11,000+
“Civilization was either more advanced than we give it credit for or aliens came and helped.”
There is actually a third alternative.
Some folks claim there is an Akashic Record or a Superintelligence that may be just an artifact of the universe or alien intelligence of some kind—and the ancients found ways to “tap into” that frequency.
No travel by anyone would be required.