If we find life on Mars, then we need to consider where this life came from. There is tremendous evidence that in the B.C. era, Mars was not in the orbit it currently has. It had an eccentric, elliptical orbit that crossed Earth's orbit several time that B.C. history shows us. At least two of these "flyby's" were extremely close, close enough that both Earth and Mars could easily have exchanged material between them. Check out https://www.creationism.org/patten/PattenMarsEarthWars/index.htm and a breakdown of this info, 'Mars Flybys: 7137-701 BCE' at https://www.migration-diffusion.info/pdfdownload.php?id=504&file=1.