I think it's likely that early Mars produced some simple microbes. It didn't take long for life on Earth to get started and the early conditions on Earth were not as nice as they are now. As conditions for life on Mars got worse, these simple lifeforms probably died out long ago on most of the planet. If we do extensive digging where the water once was, and use microscopic imagers, we will probably find some evidence of extinct microbial life. I think our best chance of finding life that is alive now, is under the ice at the poles. I would be surprised if we don't find any simple life living under the ice.