I think I'd take the Martians to see us taking care of one another.
I might show them parents walking with a new born baby on their
shoulder late at night, trying to get the baby back to sleep. Or
volunteers hammering together a house for someone whose life will
be changed by it. Or the way we automatically stop for someone who
has tripped and ask if they're ok. Or perhaps how an entire nation
gives food and medicine to a country across the ocean. It's when
we're caring for one another that we're at our best.
When we're at our best we're also the most human. You wouldn't
understand us if you never saw us at our best, any more than you
could understand a basketball if you only saw it deflated and flat.
We are only human because we're connected to other humans. If you
were brought up on a desert island, you would grow up and hardly
be human at all. You'd have no words and no ideas beyond which plants
taste good and which bugs taste bad. You would be perhaps the worst
example to show a Martian trying to understand us humans.
We are human because we are connected to other humans. And why
do we connect? Because as humans we care about each other and about
our world. Statues don't care what happens to them. Robots don't
care. Humans do. We care together.