Is Moonriver layer 1?

Excuse me, I'm a bit confused about the technical details here. Could you please clarify for me if Moonriver operates as a layer 1 blockchain? I'm trying to understand its architecture and how it fits into the broader blockchain ecosystem. It would be greatly appreciated if you could explain this in simple terms, as I'm still new to the intricacies of blockchain technology. Thank you in advance for your time and assistance.