Can't get past the giants
Solution 1:
Giants cannot be taken down without the proper gear and the proper levels because giants have a preset level over 30 at the start and will fight together with its own kind and mammoths. Do not fight them under level 10 unless you want to do the hit and run to the Whiterun guards tactic.
Before doing anything like going out into the wilderness save.
The route you are taking are beyond the roads you are supposed to pass. Do not take shortcuts through open fields or over hills and mountains.
The first thing you should do before going to the Greybeards is have decent gear and skills in any of the ways of combat. You can either go with magic or physical damage. A dark elf seems to be good with magic and the bow. So A combination of those could work nicely for you.
Suggested builds:
Conjuration bound bow and stealth is good. With this build you can create atronachs to tank for you.
Pyromancer with conjuration. With this build you can be a Destruction and Conjuration build so you can have a tank while pummeling them with fire magic.
Assassin Restoration Vampire. I saw this somewhere and it seems to be good although I have never gone the vampire route.
sword and shield with restoration.
It depends upon your play style on what you want to do with your build.
My build was a sword and shield style where I can stagger opponents using my shield. At the level I was at for Blocking, it was easy to block the attacks and do a block stagger attack method.
I leveled up my Blocking by having a shield then having a Mudcrab (killed it after level 10 Blocking), bandit (killed after level 30 Blocking), attack me until it was a high enough level. Then the giant got me to level 50+ in blocking. Then I killed it. Don't do this against multiple giants. Or you will be in space.
Solution 2:
I can't remember any giants on the way to meeting the greybeards. It's an open world game, just avoid them by going a different path.
Giants are among the most dangerous enemies in the game and it would be strange that you needed to defeat several of them for one of the early main story quests.