Definitely not, one of the first things you learn when becoming a freelancer is that it's very important to specify in the contracts what the deliverables are e

Definitely not, one of the first things you learn when becoming a freelancer is that it's very important to specify in the contracts what the deliverables are exactly, specially regarding copyright, source files, photoshop file vs final product, etc. The reason is because in most cases (this is ~1 decade old personal research/opinion) unless specified the client is paying for access and use to the final product you make, not necessarily for anything else. This is the sane thing though, but in business in many cases you might want to also receive the blueprints, source code, assets, copyright, etc. This might be "obvious" depending on the industry and case, but that means it's not obvious at all in a general sense. For example here, the company (and that might be why Microsoft backed up) might be happy with just being able to use the work, even if they don't have an exclusive contract or are the copyright holders of that particular bit. I do agree that it seems Mojang had implicit permission at least to use it, but not exclusive/full copyright/etc.