$500 is too low, but here is a reasonable beginner set for $600.
Canon refurbs come with a 1 year warranty, just like a new camera.
"Budget is tight, about $500."
Yes that is a little tight. Save a bit longer or try the Canon referb store as per suggestion above. But the Rebel to get is the Canon EOS Rebel T6i DSLR Camera with 18-135mm Lens. It will stay with you for a long, long time. This Rebel has all the current featuers of any Rebel.
I'll echo ebiggs on the T6i. It is not just the most current Rebel, it is also the first major model-to-model improvement in Rebels since the T2i replaced the T1i. Autofocus in particular is vastly improved vs the T5i.
"What are your opinions on the rebel SL1?"
IMHO, it is too small for me. I am 6'3" and 220lbs. Are you a smaller person? If so you may like a Rebel SL-1 but I would suggest you try one first. I use some pretty large and heavy glass which is another reason I wouldn't buy an SL-1.
This is personal opinion and you should really try one.
If you don't mind buying an used camera/lens combo, you can find a T2i/T3i with kit lens in your local market asking around $250- $300. Then spend some $$ buying a 50 1.8 STM for portrait/low light photography.
T4i has touch screen features but you may have to pay a little bit more. May be $400. Then you have $100 left for a 40mm F2.8 pancaske lens.
If you only shoot stills, you have a lot of choices with your $500. May be you can consider a Canon 40D($200) or even a FF 5D(350). They produce very very good images if you put on a decent lens.
BTW, you may spend $50 or less buying a vintage manual lens e.g. Helios 44-2 55 F2 and an adapter to use it on a crop sensor camera (not on the 5D - mirror crash). It's a lot of fun.
I noticed one of your uses is "pictures of boyfriend surfing". Be VERY careful near salt-water. Salt-water will kill the electronics.
We've had a few bad stories of people who wade out into the water -- or just get too clsoe and a big wave comes crashing over them and that's the end of that camera.
It is possible to get completely waterproof "underwater" housings -- but those are expensive for a DSLR.