Now that the presence of liquid water on the Martian service is no longer speculative, it seems highly likely that at least microbial life will also exist there, and perhaps even some plants or lichens or other non-animal life forms.

This image shows water ice, but we now know liquid water (salty brine) exists as well at least during the Martian summer.

    In addition to making the probability of present day Martian life high, liquid water also makes human missions much more attractive.  The perchlorates also present on the Martian surface are also valuable as a component of rocket fuel.  Typically ammonium perchlorate serves as an oxidizer and aluminum as a fuel in solid rocket boosters.  Hard to say what the fuel might be on Mars but at least they’ve got an oxidizer.

     I suspect that if we make it to Mars we’re going to eventually find out we weren’t the first to visit.