The question we have right now is that "can Mars host life now?"
We're still not sure yet. However, if we're not speaking about humanoids inhabiting Mars, then there might be a possible chance that there are already existing life forms already in Mars' subterranean reservoirs due to some evidence that there is liquid water locked away in it.
But for now, the red planet remains as an eerie time capsule of the era when Earth formed into what we know of it today.