Even if we assume your premise, so what? If Alien is a remake of It! The Terror From Beyond Space, does that make it a bad film? Westside Story is a remake of Romeo and Juliet - is it thereby an inferior movie? Or Bridget Jones’ Diary, which is an updated Pride and Prejudice?
There are a good number of movies and books that are reworkings of earlier stories - Clueless is Emma, Ten Things I Hate About You is The Taming of the Shrew, Ran is King Lear. Stephen Fry wrote Revenge, which is such an unapologetic rewrite of The Count of Monte Cristo that he even gave his characters names that were anagrams of their Dumas originals.
Maybe I’m misunderstanding you, and you’re not saying that Alien is bad because it’s a remake of It.
The fact that it was basically a modern version of the '40’s serials as well as science fiction adventure stories going all the way back to the 30’s was a genius move.
Took my now 91 year old mother to see Indiana Jones when it first came out. She was not overly impressed,she thought it was something she’d already seen in her youth.
When Raiders of the Lost Ark was being critized for being heavily derivative of the serials of the 30’s and 40’s, Lawrence Kasden invoked the following (I forget the actual derivation):
“If you steal from one source, it’s plagiarism. If you steal from ten sources, it’s research.”