Check out the Copernican principle:

the Copernican principle states that humans, on the Earth or in the Solar System, are not privileged observers of the universe, that observations from the Earth are representative of observations from the average position in the universe

The idea is that an individual is probably pretty close to whatever is “normal” for its group. Like, most people are around the normal height for their country. So we’re probably pretty close to whatever “normal” is for a terrestrial intelligence.

Could there be other forms of life that are wildly different from us? Definitely. But we probably aren’t special. Statistically speaking, they probably aren’t either. So we’re probably fairly similar.

This theory was generated from a sample size of one, so it may be totally incorrect.