Ya gotta avoid their attacks. Then, strike them when they least expect it.

consider trying other games too. i've always been pretty bad at street fighter and mortal kombat, then i tried tekken and it clicked for me a lot better

https://www.youtube.com/watch?v=_R0hbe8HZj0 If you're a video watchy person, I found this to be a really good overview on fighting game fundamentals.

well, I am not good but consider I can usually finish all the combo trainings 100% so my execution is quite okay. (I quit fighting game cause the button tapping is quite noisy, so no more fighting game after my son was born. )

• street fighter have a couple arch type, ryu/ken is shoto and they have actually different play style even though their basics looks similar.
• for any fighting game the distance that your opponent's attack can reach is very important. a good player can simply whiff punish you and throw jabbing you because you don't understand the +/- etc after a blocked/whiffed attack.
• hit confirm is also important, which means a simple combo that you can start when you have advantage, but not too "negative" when it's blocked. (training mode can show these info) Where the first 2~3 hit of your combo is safe and once you get better and landing those 2~3 hit combo, pick something that allows you to cancel into special moves, knock down or throw(which is also a down). All the more fancy complex combo is not really useful if you can't even land a 2~3 hit combo on opponent.
• punishing specific match up's bad move, ie. a fireball at wrong distance allows opponent to jump in and lands full combo out of it. you have to do training mode a lot and study your match up.
• and finally, study the neutral game, where both side starts from distance that all normal attacks are out of range, what can you do from that point of space and what opponent's char can do from their space. If you keep getting beat by opponent's certain move, rewatch the replay, check their input, record that input to a training dummy, and find what you can do as counter.

It's a huge time sink and there are also cheaters(on pc specifically), so good luck.

im also pretty new to fighting games.
but from what i heared, playing arcade mode is verry diffrent from playing against other players.

especially in older games hi level cpus tend to fight dirty,
using input reading and op boss characters.

input reading cpus basicly have inhuman reflexes,
and will counter big comittal attacks like jumpins or tatsu as long as they are free to move.

so throw out non-commital pokes, untill they do something you can counter.

if its the bosses you are struggeling against,
only perseverance will help. (unless you find a move the ai cant deal with)
they are designed to take your quarters.

Why play the old iterations? Is there a reason? I think the newer ones are more "beginner friendly"? With training modes and such.

A lot is going to vary depending on the exact game you play, strategies and game mechanics can be super different. The best way is to find a character that you really like and focus on having a good time. It's a genre built off of learning from failure, so you've got to try your moves in different situations and see what works. You can practice moves against bots to find what situations they work well in, and plenty of people post combos you can learn online. Just gotta lose a lot.

i just mash