Krdytkyu

The assumption that Thranduil is more noble is conveyed in the movies by the fact that he has blonde hair and more "lighty" demeanor.

As far as I understood Thranduil inherited the Elven kingdom of Thingol. Thingol (earlier called Elwë) saw the Light of Valinor. However, Thranduil is not a descendant of Thingol afaik and he probably never went to Valinor. So why is he any different from other Elves that "did not see the light"?

Afaik, the only Vala that he might have met is Oromë; is his possible meeting the only reason as to why he is more noble? This is suggested in this video:

However, this could also have been the case for other old Sindar/Woodland Elves.

Or is his "nobility" due to the fact that he was born in the First Age and thus one may assume that all Elves born in the First Age would be nobler (or blonde if you will) to Elves born afterwards in Middle-earth?

This is answered in the Galadriel and Celeborn material in Unfinished Tales; Appendix B, The Sindarin Princes of the Silvan Elves:

In Appendix B to The Lord of the Rings, in the headnote to the Tale of Years of the Second Age, it is said that "before the building of the Barad-dûr many of the Sindar passed eastward, and some established realms in the forests far away, where their people were mostly Silvan Elves. Thranduil, long in the north of Greenwood the Great, was one of these."

Thranduil is therefore one of, or at worst descended from, the Sindar Elves of Beleriand in the First Age, who never saw Valinor but who nonetheless did make the Great Journey and come to Beleriand before the Rising of the Sun.

His people, on the other hand, are predominately Silvan Elves (not Sindar) who were of a different, lesser people. The specific difference is also defined in the same source, this time Appendix A, The Silvan Elves and their Speech:

The Silvan Elves (Tawarwaith) were in origin Teleri, and so remoter kin of the Sindar, though even longer separated from them than the Teleri of Valinor. They were descended from those of the Teleri who, on the Great Journey, were daunted by the Misty Mountains and lingered in the Vale of Anduin, and so never reached Beleriand or the Sea.

Finally, the text of The Hobbit summarises all of this (but note that it dates to a time from before the full conceptions of the relationships between the different Elven peoples were fleshed out):

They differed from the High Elves of the West, and were more dangerous and less wise. For most of them (together with their scattered relations in the hills and mountains) were descended from the ancient tribes that never went to Faerie in the West. There the Light-elves and the Deep-elves and the Sea-elves went and lived for ages, and grew fairer and wiser and more learned, and invented their magic and their cunning craft, in the making of beautiful and marvellous things, before some came back into the Wide World. In the Wide World the Wood-elves lingered in the twilight of our Sun and Moon but loved best the stars; and they wandered in the great forests that grew tall in lands that are now lost.

So yes, Thranduil is more noble than his people, because he is descended from a different, more noble, Elven people.