You need to rewatch the first season of TOS in production order. the first 12 overall are as 'connected' as anything in the first season on TNG.Also TOS episodes were standalone to the point there was little if any development between them that it would be difficult to contradict anything. Each episode started off with there being a status quo and ending like it. The first episode Chekov appears doesn’t even treat him like a brand new character that gets a notable introduction, he’s just presented as if he’s already been around. Same with Bones after the pilot. Contrast that with TNG, where its first episode actually does run with the conceit of the characters being on their first mission and characters getting to know or meet each other for the first time.
