How are we related?
What am I?
The four objects we see depicted here are:
A (wooden) BOARD, a STONE, a (Post-It) NOTE, and a (playing) CARD.
These are related to each other in that...
...they can all be prefixed by the word KEY to make other words: KEYBOARD, KEYSTONE, KEYNOTE (speech), and KEYCARD.
So I guess that makes 'you'...
...the key to this whole puzzle!