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He must have been, if his people refused to leave him behind. They were promised paradise if they continued- it takes a lot of loyalty to stay behind for just one person. In my experience, that kind of loyalty is only inspired by love.
After Thingol returns with his new wife Melian, they set up a new kingdom together. Melian teaches the elves of the wonders of Valinor, and introduces the sophistication of the Valar's ways. Keep in mind, they are working with elves who have had no education, no inkling of what culture or sophistication is. They've never seen a real society, or even a real building. But under the directions of Thingol and Melian, they set up one of the greatest kingdoms in Middle Earth.
#3: HE IS PROTECTIVE
Some might take Thingol's refusal to help in the Silmaril Wars as selfishness, or perhaps even apathy. But I interpret it as simply being protective. He is doing his best to keep his people separate from a war that has nothing to do with them. He is wise to do so- for what is the war other than a fight over three jewels? Yes, those fighting the wars were trying to defend their people and drive Morgoth's evil from the land, but Thingol knew that if he entered the war, he would have to side with someone. And doing that would mean making an enemy of one or more of the other factions of elves.
It isn't as though Thingol is afraid of battle. He and his armies had driven many clans of orcs away from their lands many times. Before the Noldor returned to Middle Earth, Thingol's people were already holding their own against Morgoth.
Because of this, I see Thingol as not so much selfish- but rather self-absorbed. He cares about his people and will defend them readily- but he will not engage in a conflict that is not his own.
#4: HE IS A GOOD FATHER (Sort of)
In the story of Beren and Luthien, Thingol plays the stereo-typical overbearing fairy tale father. But if I were the ruler of a realm and some bedraggled homeless bum showed up uninvited and tried to romance my daughter, I don't think I'd respond well either! Thingol's interactions with Beren when he finds out about his and Luthien's secret relationship are pretty much spot on for a protective parent in that situation.
Of course, Thingol makes mistakes, like any parent does. But being as he is a prideful king, his mistakes are a little bit more extreme than most parents. Locking his daughter up in a house in a tree, for instance, was not the best thing he could have done for her, even if it was to 'keep her safe'. But still, there is no denying that he is a loving father. When Luthien gives up her spirit to death after Beren dies, Thingol goes into a deep depression. His daughter meant the world to him- and it was only her return from death that saved him from his illness.
(I should note that when an elf becomes depressed, it is extremely dangerous for them. When they become too sad, it is actually possible for them to die of a broken heart, as was the case with Feanor's mother. Tolkien describes Thingol's depression as a 'winter of the heart', and it is only Luthien who heals him. I imagine that Thingol may indeed have been close to death, and it was only the return of his daughter that saved him.)
Later, Thingol adopts the young human child Turin, who is a relative of Beren's. He did it in honor of his son-in-law, and eventually came to love Turin as he would have his own son. This, I think, was very kind of Thingol. He didn't have to take Turin as a foster-child. He could have simply sheltered the boy from his enemies until he was old enough to take care of himself. But no, when Thingol first meets the child, he picks him up and sets him on his knee and declares before the whole court that he has adopted him. All the kingdom was amazed, for until that point, such a thing had never been done before between elves and men.
#5: HE IS VAIN
Alas, though I have praised his virtues, I must also speak of Thingol's faults: that is, his pride and vanity.
It his pride that causes him to reject Beren at first, since Beren is a mere mortal, and Thingol does not like to deal with humans. Thingol's pride delayed their union, and I imagine the guilt of that is part of what drove him into depression after their deaths.
When Luthien entrusts one of the Silmarils to her father, Thingol resolves to have it set in a necklace for himself. Now to be fair, this is partly because the Silmaril is all he has left of his daughter. But I suspect it is also because having a Silmaril was a great boasting right. The entire world was fighting over these gems, and the fact that he had one had to be an immense source of pride for him. So, ignoring the council of his wife, Thingol commissions the Dwarves to craft a necklace for him, using the Silmaril as the centerpiece.