A legal entity is separate from the individuals or organizations forming it. Org has powers to sustain itself after the founders depart. Org has the ability to enter into contracts, borrow money, pay taxes, have liabilities that are ordinarily distinct from those of its incorporators or members. Org's move to a non-profit corporation helps to limit the personal liability of directors. Bylaws and state laws are related.
Bylaws are similar to a constitution.
The US President leads a free nation while operating under the confines of certain laws. The president is not free to do anything he or she desires. A freestyle attitude can prevail within certain elements of the FreeTeam. Org, but some amount of structure, established rights and procedures are necessary as an overall organization. Bylaws can be revised and amended.