I want to run a Low-Magic Campaign for 5e but I am struggling to find answers

TLDR; I think magic is not magical enough in a typical DnD world. Magic should feel strange, rare and magical**. How can I build a low magic world around these assumptions?**

Before you read: I assume arcane magic is hard to learn and master. Like rocket science, quantum physics.

Hi everyone! Me and my 5 players ended our 6 months old campaign last week. It was a high magic, high fantasy campaign which the party was basically gods. It was fast paced (players reached 20th level in 6 months) and combat oriented. But I thought it was lacking RP. And I believe the reason for that was players could buy any magic item they want or craft their own magic items easily, solve every problem they encounter with easily accessible spells. I constantly had to invent new monsters, traps, problems etc to challenge the players and this exhausted me. So now we want try something different than "saving the entire world using easily accessible magic" type of story. We want something much more minimalistic and rp based.

For this purpose I am building a new world called "Terran". In Terran magic and magical items is rare. Especially arcane kind. Archmages are both very rare and powerful. Like Saruman from LOTR. Less powerful wizards do exist but they are rare and often doing a specific utility job. They can cast "Sending" rather than "Fireball" for example. As for combat focused wizards, they are often used as bodyguards serving important nobles, kings and emperors rather than soldiers in army. And they are very expensive and time consuming to train as a result they are rare as well. As for training of wizards, it is done through apprenticeship rather than studying in mighty magic academies. There are only 2 magic academies in the entire Terran (which is roughly the same size and shape as our world) but as you can imagine they have strict rules to hire new students and they are very expensive. In short all arcane magic users are rare, expensive to train and respected in the society.

Divine magic users are rare too. Not as rare as wizards do though. Not every member of the clergy is given divine powers by their deity.

Druids are rare, living as tribes and they dont share their knowledge outside of their tribe. Warlock and sorcerers are originally rare in most settings so i left them as they are. I dont know what to do with bards though. For me bards music is somewhere between divine and arcane. It's a little problematic to decide.

So my problem starts with learning new spells as you gain a level in wizard class. For divine magic users is easier to solve. We can say their deity simply wishes to give more spells or the divine magic users learns new prayers simply by memorizing them. But as PHB states for wizards "Each time you gain a wizard level, you can add two wizard spells of your choice to your spellbook." But PHB does not give any information about how they do it. One day wizard knows only 5 spells and the next day knows 7? Did he/she learn in his sleep? Is he/she over 9000 IQ? I need an explanation for wizards learning new spells as they level up. And as for the copying spells with spell scrolls PHB states

" For each level of the spell, the process takes 2 hours and costs 50 gp. The cost represents material components you expend as you experiment with the spell to master it, as well as the fine inks you need to record it. Once you have spent this time and money, you can prepare the spell just like your other spells.

A wizard spell on a spell scroll can be copied just as spells in spellbooks can be copied. When you copy a spell from a spell scroll, you must succeed on an Intelligence (Arcana) check with a DC equal to 10 + the spell's level. If the check succeeds, the spell is successfully copied. Whether the check succeeds or fails, the spell scroll is destroyed. "

I think it is really unrealistic to assume with only 2 hours of practice and a nights rest you can hurl fire out of your hands casting a devastating "Burning Hands". And what if you fail your Arcana check? You wasted around 100 gp (burning hands spell scroll price+ ink and paper) for nothing. It is really frustrating as well. And where these spell scrolls come from in the first place? When you mastered "Burning Hands" spell with only 2 hours of practice and 100gp investment can you forge "Burning Hands" spell scrolls to sell to other people by yourself? So thinking my previous statements about Terran if this is the case why not anyone with enough money and mental capacity in Terran is not a wizard?

As you can tell I am a confused and unsure of what to do. What do you think about running a low magic campaign? Do you have any advice? Am I exagerating about what I am thinking? All help is appreciated :)