OK u need quite the bit of work but don't
Feel bad every1 has gotta start sumwhere....
1st off u were kinda just flailing around, like in the 1st vid. Mario would grab u cuz u would run or dash dance right in front of him but do nothing. All your movement should have a purpose.
2nd u was attacking with the shine but u weren't rilly waveshining so it was pointless. U have to learn those follow ups. Also the shine is a beast move but I wouldnt make it my choice of approach if I'm just starting to learn about approaching. Approach with nair shines. Which brings me to my next point
3rd is tech skill, ur tech doesn't seem to be 2nd nature yet. I feel as if ur still thinkin about how to l cancel and wavedash. This needs to be practiced with any char. Me personally I'm just starting to improve my game and my problem for a while was I was practicing tech on a flatscreen(laggy) so I would go to tourney and fail horribly lol. Now I. Got a non lag tv and it all feels so natural now. I practice on 4 chars ganon,falco,falcon,marth. Ganon for fun,falco for thunder follow ups, falcon to get use to his body weight, marth waveshine distance practice. U can practice on whoever u like but practice it. Also to help with aerial shine make the cpu bowser lv 1 put handicap on and damage ratio to .5 then put ur handicap on 1 and practice nair shine. And only practice vs cpu lv 1-3
Next work on your spacing. There is no way to rilly practice this vs a cpu because they don't move like real ppl but learn the properties of your moves. I'm still practicing this myself.
Grab aerial Is good too.
That's all I got happy smashing