Apple stands behind their products, and use the finest, most durable material possible.
The aluminum Apple Watch models feature Ion-X glass to protect the display, while the stainless steel and titanium models use sapphire crystal glass.
Sapphire crystal glass is considered virtually unscratchable. Plenty of high-end watches also use sapphire-glass faces for the same reason.
I'm sorry you are having issues with your Apple Watch Series 1. You have to remember though, the Apple Watch Series 1 has not been manufactured in quite some time, and at some point devices do wear out, and warranties expire. Apple has the Limited Warranty for 1 year, usually any defects will show up within that first year. If there's an issue that is widespread they have replacement programs for that...
Apple doesn't cover scratches. It's considered cosmetic in nature. Cosmetic issue are not covered by AppleCare nor the limited warranty. However, Apple does have the 14 day return policy if purchased directly from Apple. So if you are not happy with your purchase you can always return it for your money back. If the scratch happens after that then it was not considered a defect and caused by an accident... which is not covered under any warranty.
If purchased from a different store they have their own policies so you'd have to check with them on their return policies etc..
I've had an Apple Watch Series 5 since it first came out... not a single scratch on it. I don't have a screen protector or case around it. I'm not that careful either... normal usage. I'll probably upgrade to the latest version soon.
You could get a screen protector if your watch seems to be getting scratches.