So, you have a batch of players who are mostly new to role-playing or new to D&D specifically. Tossing a rulebook at them and telling them to make a character is a bad idea: they will have no idea which of the many options to pick. Some people think that the backgrounds I have been suggesting would likewise be confusing. However, here's how I'd handle class and backgrounds for a newbie campaign:
- all the characters grew up in the starting town (15 years experience;)
- initial choices given are three or four classes, only one of which is magical (because those include more choices;)
- all characters are trained in a profession related in an obvious way to their class.
The players just say which one they like; I'll say, "unless you want to be a different age, we can start you out at age 20, which means you've been a knight (thief, wizard...) for 5 years." Then, we start rolling stats and naming and equipping them. Characters are done.
If they have more than a passing familiarity with fantasy, they may already have a character concept that doesn't fit those simple choices. "I want to play a Beast Master, like in that movie!" "I want to be a bard, like Felimid Mac Fal in the Bard series."
They get what they want.
Maybe not everything they want, right now, but it's pretty easy for me to give them an appropriate background -- just use "beast master" or "bard" as a background, to indicate they have that kind of training -- and then find a class or hybrid/variant that will give them approximately what they want. I might ask a couple questions, like "do you just want to be more of warrior who can talk to beasts, or do you want to focus on beast speech and control?" or "do you want to be a magical bard, or a persuasive bard?"
Likewise, if the player brings up a fantasy race and says, "I want to be that," they get to be that, with the default background for that race. My point here is that if they already have an idea about what they want, but you only give them a few options, they will tell you exactly what they want, with no indecision whatsoever. If they don't know what they want, you've given them a very simple set of five choices. If that's still too hard a choice, tell them "you're a fighter". Either that will be fine, or they will immediately know that they want something else, and will tell you.
Now, once they've played with those simple choices, they may get a more elaborate idea. Maybe they'll say, "I want a warrior who can use spells." Then I'll ask, "do you want to be:
- a wizard who can fight like a common mercenary; or,
- a hero who dabbles in magic?"
Only much later will newbie players want to see the full character creation rules so that they can look for possibilities they never thought of. And that can be done while they continue to play their existing character, at their leisure, preventing a stall in the game due to option paralysis.
In summary: the choice isn't between forbidding variation or risking indecisiveness. You can give a sharply limited number of character types to start and allow variation when players know exactly what they want.