Lol! True, except perhaps for microbes on the space station. Or human biology in space.
There is an absolutely huge amount of Earth-created (non-human) life remnants on both our Moon and Mars--ejected by 4 billion years of asteroid impacts on Earth; of course, the density is much higher per square kilometer on the much-nearer Moon. In fact, samples of very early Earth-life (±4 billion years old, pre- and mid-Late Heavy Bombardment) are only available there, because the LHB destroyed all Earth-life by causing the Earth's surface to melt repeatedly.
Of course, once NASA or the private launchers finally bother to look for and uncover this abundant evidence of early life, expect fantasists to ignore completely its Earth origins and claim it to be "astrobiological"! And astrobiology will finally have its first (false) data.