What happens when we'd put some microbes there now?
Perseverance's mission includes collecting and storing samples for a return mission. https://en.wikipedia.org/wiki/Mars_sample-return_mission
b) we should have found something by now. There clearly isn't a whole lot happening on the surface of mars at any rate
b) we’re still guessing at bio-signatures; all we are confident of is there isn’t “a lot of stuff like us”, but that’s a compound claim and we can’t rule out “a small quantity of stuff like us” or “as much life as a desert but very different to us”.
As other commenters have noted, it's probably not very wise, but I imagine it would be the cheapest way to increase the chances of the continuation of life (as we know it).
(There is a hypothesis that life may have been introduced this way to earth, known as the Panspermia Hypothesis https://en.wikipedia.org/wiki/Panspermia)
If not for an asteroid, the earth might still be populated with dinosaurs. Would they have evolved to our degree of intelligence and civilization? Who knows?
The universe may
be as great as they say,
but it wouldn’t be missed
if it didn’t exist.”
But it's an interesting question. In fiction, I can recommend Adrian Tchaikovsky's Children of Time, and sequel Children of Ruin.
The surface of Mars is an anoxic toxic irradiated frozen desert.