Every Micro-Hero that has ever been seen on the world wide web was made by a real individual, somewhere out there, in the real world. Those people are the Micro-Creators. They work with their keyboard and mouse without being paid to do so, and they share what they've 'created' with others. They learn to use different graphics programs to arrange many pixels of colored light in just the right way to create their chosen micro, and when they're done they give the file a name and save it.
One thing all Micro-Creators have in common is a desire to have their efforts appreciated by others. Some micro-heroes are fairly simple and can be made quickly, while others take the creator a considerable amount of time. In either case, a little recognition for their effort replaces the paycheck they'll never get. In the forums of groups or message boards their work often goes through a sort of peer review where others may comment on their work.
Many Micro-Creators affix a "tag" to their micro when they post it. This tag is usually a short abbreviation of their screen name or user ID and acts as their signature. It is incorporated into the filename so that others who download it can remember who made which micro. A micro with the filename, Thor_Lky.gif would let you know that this micro of Thor was made by "lucky," for instance.
Credit is the currency of the creators, and in this sense stealing would be taking credit for what is not yours. The ultimate "theft" would be to take another person's work (another's micro) and post it as your own. Simple common sense generally rules the day on such matters; if it ain't yours, then it ain't yours. That's not to say that "borrowing" a piece of someone else's work is the same as stealing the whole pie, and novice micro-makers frequently "borrow." Credit to where credit is due goes a long way, and getting the permission of another to use their work is very wise.