I see 2 scenarios:

1. There is a universe-wide codex of how to behave when visiting a planet bearing a primitive civilazation like ours, most likely a "don´t interfere and influence"-like style (which e.g. could explain why so far we were not contacted).
2. There is no such codex and the "wild west" reigns. This is the for us less optimal variant, as an encounter with a superior alien race could easily be devastating for us. This is why some researchers say we shouldn´t be so naive and send signals out into space, but instead should hide as much as possible.

Hard to tell what is more likely, what do you think?