Not necessarily - Thor can blast Superman with not just lightning but also wind, snow and frost to slow Superman down. In addition, Thor can see fast-moving objects so would always be able to judge his hammer blows and lightning strikes against Superman perfectly, despite Superman moving at many times the speed of light. Thor isn’t as slow and cumbersome as you make him out to be - the Hulk’s job is to be slow and cumbersome. Furthermore, Thor has magic which is detrimental to Superman as he has little protection against it. Superman has beaten magic users before, but Thor is centuries older than Superman and probably knows what magic can really mess him up.
Superman is OP. Without kryptonite he absolutely stomps Thor. Thor might be able to track fast moving things, but nothing that is moving near the speed of light. It is simply way too much of an advantage. Thor's hammer throws are magnitudes too slow. Even lightening only travels at about 1/3 the speed of light. In regards to using wind, snow and frost against Superman, those will have a very negligible effect. Also, Superman's freeze breath can replicate all that only better. Plus his heat vision is arguably stronger than Thor's lightning.
[and just to put the speed of light into perspective, light can travel around the world 7.5 times in 1 second, Thor has never exhibited anywhere near that kind of speed]
Your point on magic is valid, Superman is susceptible to it, but I don't believe it is enough to take him down. Also, Superman has a massive intellectual advantage. Thor quite often acts brashly, which is something that a person like Superman could exploit (let alone what Batman could do with it as he works in the background)
As for protecting me, Thor could ask his father to protect me with the Odinforce, the most powerful magic in existence.
We're not bring allies into the mix. Otherwise things get massively out of hand. Then we start bringing in the entire Justice League and the Green Lantern Corps and things get simply ridiculous.
Thor crushes WW. Easily. Maybe he may not be able to protect me against all 9 at the same time but certainly he could take on each one one at a time and destroy them, as he has a huge amount of stamina as opposed to speed.
Batman - in a straight up battle (without significant prep work) Batman easily loses
Green Lantern - a good battle, I actually think that GL gets the better of him early on, but eventually gets worn down as his power ring runs out of juice
Captain America - no contest, clear win for Thor
Iron Man - Thor wins, not right away, but Iron Man really stands no chance in the long run
Wolverine - Thor wins, Wolverine being a grounded opponent really doesn't pose much threat. He needs to get in close, but ultimately can't
Wonder Woman - This is a really good match. Both have exceptional strength and durability. Wonder Woman is more agile, but Thor has longer ranged attacks plus his hammer. I'd say Thor in the end, but it would be a WAR.
Robin - no contest here, Thor all day
Flash - Stalemate. Flash can't kill Thor, but Thor can't land a strike against Flash.
Superman - Without Kryptonite, easy win for Superman. Too strong, too fast, too smart, too many weapons
Spiderman - Spiderman is formidable, but no match against Thor
That said, Thor isn't an option on the list. You can't choose him. Otherwise I choose the One Above All and it is game, set and match.