There is no contradiction between Jesus being represented by a star and by the sun. Other deities of the time had multiple associations as well.
While the following was written in reference to the Mithraic bull specifically, the same point that's relevant here atm applies equally to any divinity of the time & culture back then.
As historian of ancient Rome, Roger Beck, wrote in his essay The Rise and Fall of the Astral Identifications of the Tauroctonous Mithras, on page 240 of Beck on Mithraism: Collected Works with New Essays:
"Argument 5 The polysemy of symbols: a symbol can have several referents ('meanings'), and these can be in play concurrently. The law of non-contradiction does not apply. Thus, the bull slain by Mithras can - and I think did - signify both Taurus and the Moon. Moreover, two symbols in the same context can refer to the same thing. Redundancy in symbolism is not a mistake. In the tauroctony the bull as well as the bust of Luna can symbolize the Moon."
Even Osiris was identified with Orion, as well as the Sun (during the night, when the sun was in the underworld, Re merged with Osiris at that time), as well as with the Moon.
Horus was likewise referred to in the Pyramid Texts as the Morning Star (Utt. 519:1207, Faulkner), yet also as the Sun, when he merges with Re at his zenith point (Utt. 437:804, 455:853-54, Faulkner).
And the Pyramid Texts likewise identify the deceased king for whom the texts are written & recited, with all of the above, since he was identified with both Horus and Osiris- Horus in life, and Osiris in death & resurrection.
Other texts besides the PT affirm all of the above identifications as well, I am just the most familiar with the PT, so they are my go-to texts.
Anyway, the point is, in ancient religious thinking, it was no contradiction to have more than one astronomical body associated with a particular god.
Also, one other text which was used by Christians to associate Christ with the sun was Malachi 4:2, "But for you who revere my name, the sun of righteousness will rise with healing in its wings."