It is a celebration of many things - of a miraculous military victory over greater forces, of the rededication of our Temple after desecration by those forces, of the faith that HaShem would allow one day's worth of fuel last until more could be procured. It is a celebration of lightS and of joy.
It is NOT a celebration of the coming of the light again, because it is NOT a solistice celebration.
1. It's a celebration of a historical event. It would be like calling Columbus Day an equinox festival. It happens roughly around the same time of year, so... (Passover is a spring festival, and effort is made to keep in the spring time. Of course, that keeps all the other holidays in their seasons, too.)
2. The idea behind solistice festivals, from what I gather (and if I am wrong, *please* tell me) is to either call the sun back because it's gone away OR as a reminder that the light will return - or to light the long dark night. None of those work for Chanukah. In the first two cases - it is a daily miracle that the Earth rotates and the sun rises every morning. EVERY morning. No matter the length of the day. To believe that God needs reminding or that we need reasuring makes no sense from that perspective. And Chanukah lights do not need to burn for more than an hour on weeknights (slightly longer on Shabbat), and they are lit as soon as possible after full dark. That doesn't do a good job of lighting the long night - especially since one is forbidden to use them AS a source of light. Their only purpose is to publicize the miracles.
Also note that Chanukah can be as early as November - three weeks before the solistice, while the days are getting progressively shorter. So they really can't symbolize the return of the light.
Not every culture has a solistice festival. Chanukah is a bright and lovely celebration in its own right (and I wish very, very much that it happened in some other month besides Kislev, because then none of these comparisons would have happened.)