LOL! Yes, there are people who think humanity would be a “contamination”!
Hitler said human beings were “planetary bacilli.”
Humanity isn’t the problem, it’s the 90% (by number) of cells in and on your body which aren’t you. We each carry a vast colony of other life forms, some of which could very well exploit environmental niches on Mars and possibly wipe out the very life forms we want to study.
Where I come from that’s called dumb. YMMV