Is it possible that the purpose of mankind is to transport a lower lifeform (bacteria, roach) to Mars, etc.?

Not sure, but I certianly hope that there is more meaning to our existance thatn that. Who's to say really? I think our lives have whatever meaning we assign to them, personally. I wondered before what if the Earth itself is just one little atom in a much larger body of life.

If God wanted such lifeforms on Mars, he would create them there. Perhaps you do not believe in creation, but mankind was and is a special creation of God. Not like the angels, who are completely spiritual in nature or the animals who are completely physical, but uniquely mankind is both. We have a much higher purpose than transporting bugs to Mars.

Are you asking that we transport you somewhere? Don't worry, the cockroach will make it to Mars before we do.