It is good for beginners to learn as much as possible, but the really hard part about choosing first handguns is understanding the compromises that are involved in selecting handguns for different purposes. These compromises include: size vs concealable, power vs controllable, and general purpose vs specific purpose. It takes a lot of experience to make judgements about balancing these choices, and this is where the experience of a good instructor is invaluable.
I have helped lots of people with these issues, and even though individual requirements are quite important, I can still give an overall summary of what works. A first handgun should either be striker fired 9mm that is big enough to get a good grip on, or a .22 target pistol. Most people who want to shoot well will eventually need to own both of these, and it does not matter that much which one comes first. A traditional double action 9mm is also acceptable, but the two different trigger pulls causes more problems for beginners than many people expect.
If someone wants something more powerful, or something much smaller and lighter, or a single action cocked and locked auto, then those are all fine choices for a third handgun, but only after the basics are mastered with something easier. Here are some popular first choices which work out poorly in my experience: a lightweight .38 snubnose, a very small 9mm, an even smaller .380, a 1911, anything in .40 or .45. These are all great guns, but they are not good for learning the basics, they are good for someone who has already learned the basics on an easier platform.
For someone who really needs the first gun to be concealable, my first recommendation is something Glock 19 sized that allows for a good grip. If it needs to be smaller, then a Shield or a 365 XL are acceptable. But anything smaller works better as a third or fourth pistol.
