Because it's rare for undergrads to have research experience, it makes a big difference in grad school admissions. The admissions committee guesses how good a researcher a student will be based on grades, test scores and professor recommendations. If the student has actual research experience, there's less guessing to do.
A lot of professors have smaller projects that are part of their overall research that they can give to undergrads to do.
But, this isn't really helpful to you now. Your question is really "What are my chances?" and I can't tell you. For the people at the top and bottom, grad school admissions is easy to determine. But for those in the middle (I was one of them), it's almost random. Like many things in life, now that I've been through it, I know what I should have done.
If you want to go to grad school, then apply. Not applying is a 100% chance of not getting in. But try looking for schools that do research in what you're interested in, and look at schools outside of the top rankings.