Aupmanyav
Be your own guru.
Wikipedia says Mithras was born out of a rock. I do not think it mentions the various things that you list here. Sort of surprised. There must be a better source of information about Mithras than Wikipedia. Krishna remained in his birth place, Vraja, during his childhood. And he is not a sun god. Vedic Mitra is totally different, just a sun god, one of the seven/eight/ten/twelve (at various times) sons of god-mother Aditi.There are many here who realize full well that the Christ's appearance 2100 years ago was that of the Sun God ..
What intrigues me is the date for Christmas. Vedas never celebrated Winter Solstice. It was considered to be the bad part of the year. They celebrated Spring Equinox and that was the beginning of the year for them. Is Christmas really the Spring Equinox which has moved three months ahead due to precession? Vedas have record of such movement. At one time Spring Equinox occured when the sun rose in the asterism of Orion. Now it rises in the asterism of Pisces.
Can I suggest that you read this: Lokamanya Bal Gangadhar Tilak — The Arctic Home in the Vedas — Chapter 12Who are some of the other Solar Deities? I count Horus, Krishna, Christ and the Lamb of Revelations. What others?