I’m pretty sure it is. I recommend you research multiple online sites and markets like eBay etc to check what similar devices go for with the collectors crowd - best success and when you’re done, please let us know how much you ended up selling it for!
I'd be curious to know that original iPhone's battery condition, but I imagine nobody will ever open the box to find out. A web search suggests a sealed box 2007 iPhone is likely to have a significant value, perhaps $10,000+ if the right buyer bids for it, but let's not forget several million were made.