You either believe Einstein and his theories of relativity or you believe that UFOs are mechanical and biological entities that have travelled hundreds of light years to cruise around earth but never make actual contact. You can’t beleive both.
Put another way. Find the Chairman of the Department of Physics from a major university willing to testify under oath before Senator Rubio’s committee that in his or her opinion these UFOs can really be such a biological and physical entity. Doubt you would find one. If such a person were to publicly give such testimony , he would be laughed off campus.
Thinking someone had to fly here on a space ship is like a 18th century Californian believing the only way to get from NY to LA is by covered wagon.
Consider the Alcubierre drive, a speculative idea by theoretical physicist Miguel Alcubierre for a warp drive based on Einstein's field equations in general relativity. Granted, the negative energy required is beyond present technology, but it might be plausible in a generation or two. Experimental tests are apparently being developed.
More broadly, the connections between relativity, gravity, and quantum mechanics are not yet resolved. That gap leaves major cosmological questions open and could generate new physics that offers a practical basis for faster than light travel.
Theoretical physicists live for such possibilities and I am unwilling to bet against them. After all, just when classical physics seemed to have all the answers, along came Einstein, pulling at loose ends and revolutionizing physics at both the subatomic and cosmological scales.