How come some of the mutant characters in the original x-men comic are not included in the last episode ?

I think they all actually finally make an appearance, but not as they should have. Cyclops & Marvel Girl (aka Jean Grey, Phoenix) have been there since the first movie. I know Iceman was in the second, but they haven't done him justice, making him a little know-nothing kid instead of a founding member of the team. They are finally adding in Angel, but I don't know if he'll be true to the comics. Also, Beast, the last of the original X-Men, makes an appearance, but as he appeared after his secondary mutation, rather than in his original form. These 5, along with Professor X, of course, comprise the original X-Men, & are finally all appearing.