Painted Wolf and Peng both gave much more sophisticated answers than I could, but they sound about right.
My gut instinct tells me that there are absolute (for humans) moral rules. Things like rape and murder and slavery are always wrong. Things like treating others kindly, helping others when you can, is always right. But due to differing definitions and cultural biases, it's hard to determine exactly what constitutes murder, etc.
In other words, yes, I think there is probably a correct way for humans to act, but that we don't exactly have the ability to know what it is all the time, and so it's best to understand that there's gonna be wiggle room in real life.
How can you believe in absolute morals or something that is good or evil to everyone if you don't believe in an objective meaning to life?
No, but that doesn't mean I think life is meaningless. Just everyone defines what is meaningful for them. My meaning to life is to be happy, to help other people be happy, and to leave the world a better place. That is what I strive for in my life. I don't think I need god to exist in order to have that meaning.