St. Nicholas was a mythical character
I don't think so. Wheeler & Rosenthal in their "Saint Nicolas: A Closer Look at Christmas" give some details about the historicity of St Nicolas in their first chapter.
Many of the acts attributed to Nicolas are probably embellished, but not all.
The 151st attendee listed in an AD 510 manuscript of attendees of the Council of Niceae was "Nicolas of Myra of Lycia."
A neat link: A Nicolas Timeline
"St. Nicholas was a mythical character"
Oh, no, my friend, very, very real.
Tell that to Arius and his broken nose.
I think I'll join the crowd and ask what's the evidence for your assertion?
On one of the threads posted on his feast day there was an interesting comment that we remembered him for all those early centuries even though there is no written record of any of his deeds or even a bureaucratic record of his existence. Yet, he was still remembered in those early centuries. The gift giving as a symbol of the big Gift caught on very early. Even people outside his "hometown" attributed it to him. Being human, you'd think somebody would have tried to steal the idea and attribute it to "their" guy to embellish someone else's reputation.
It really isn't any surprise that no written record exists that mentions him. If any written records of a bishop outside the largest cities, that's a pleasant surprise. Does any record of any bishops of Myra after Nicholas' time exist? How about any record of the leaders of the seven churches written to in Revelation, also from what is now Turkey? Consider the history of conquest of the area in the following centuries. Maintaining written records was probably not high on the 'to do' list when people were trying to survive back and forth conquest.
Yeah, there is no written record. Everybody has openly acknowledged that right from the start. The same is true for the bulk of humanity. That does not mean they did not exist.