Cybertron

You were an astronaut and one day you went on an expedition into space, but unfortunately your rocket crashed on a planet unknown to you, which was made of iron and was partially covered with greenery, already natural, like on planet Earth.
Fortunately, your landing was completely unnoticeable for this world, as if it had never happened, and the rocket landed in dense thickets, so no one should have noticed anything (and they didn’t notice).
And now you are on a planet inhabited by giant alien robots that can transform into vehicles.
To make your stay here useful, you collected various materials for study, whether it was a plant leaf, a stone made of iron, or an unknown liquid, but very little so that it was not noticeable.
Getting anywhere was difficult: everything seemed gigantic from your perspective and far more complex than human technology. However, your smaller stature made hiding and other tricks easier. You'd rather not know what would happen if someone saw you.

And everything changed when you explored the spectacular building that was located on the surface.

There were few such giant bots in the space around you.