Steem is from esteem, which is to show respect and admiration for another. You show this by up voting and interacting on Steemit. It is also a homophone for "steam" which naturally rises, and the hope was for voting to cause the best content to rise to the top, and of course the hope of a rising price for STEEM. The logo came after the word was decided upon. This info is from my memory of things read from the steem team over the last 2+ years of being here everyday.

Interesting crypto token name choice! It worked out well for Green Day so maybe it will be the start of something big for you too. :)