SF4 is still one of the simplest fighting games out there right now I’d say. Rising Thunder is on its way and that game’s also rather simple. I feel other fighting games while sometimes easier on execution usually make up for it by having way more mechanics/systems making them overall much more complex than SF4. I see people recommending SF2 as well, that game is definitely easier to pick up and play too.
I’d say some things for beginners of SF4 (and SF2, just ignore the focus attack and ultra combo) to focus on would be…
-Pick a character to stick with after you’ve tried out everyone. Sticking with a character is a great way to improve quickly. Some characters are more suited for beginners but you can get pretty far with almost every character with basic fundamentals
-Get used to the movement of your character, especially on the ground. This is extremely important as if you aren’t confident in your character’s movement options on the ground you are going to resort to jumping as your primary way of moving, which is easily countered by good players.
-Learn what all your normal moves do, their ranges and what they are best used for
-Same with special moves, super combos and ultra combos, but also practice them until you can pull them off without having to think about the motions
-Practice blocking jump-ins, crossups, overheads and low attacks. Also practice throw teching and focus attack-backdash. SF4 doesn’t really punish blocking outside of chip damage from special moves, so good blocking is not only very effective but outright vital.
-Learn your anti air moves and when to time them. They are dependent on the character but people who approach just by jumping will be handing wins to you on a plate when you learn this.
-Learn how to punish unsafe moves on block or whiff. They don’t have to be combos, think of combos as optional extra damage; if you can’t get in a situation where you can deal any damage how does learning a combo help? Once you are comfortable with the concept of punishing, combos become easier to implement.
There might be some other basics missing here, but I hope this helps