Most RV manufacturers don't bother with anything more than a couple of sheets of paper telling you how to winterize it and a few other simple things.
As far as appliances go, manuals for stoves, ovens, water heaters, furnaces, and other items are readily available on the internet. Almost all PDF format and easily downloaded.
But first, you need to go thru the camper and locate the ID tags for every individual piece of equipment to determine the brand and exact model of it. With a stove, you will need to remove the top (usually pushing hard to the rear and lifting the front), with a fridge, it is usually inside on a sticker, sometimes on the back side accessible thru the outside vents, and with water heaters, it is on the outside on a sticker, just open the door. Take pictures of everything, start a separate album on your phone for the camper.
The site below is a very good source of manuals for many RV related pieces of equipment.
Service Manuals
Owners Manuals
There are many other sites, you might post your final list, we might find it faster than you, and provide links.
As someone noted, just ask if you need to know something.
There is a Cascade model made by Host Industries, I am not sure if the Cascade you bought was possibly built by a predecessor to Host or not.
There are two Truck Camper specific forums that may be helpful. They are more oriented toward hard core offroading and overlanding, but cover a bit of everything.
Truck Camper Adventure
Truck Camper Magazine | 2022 Truck Campers, News, and Reviews
With the economic hard times that we have been thru in the past, especially in 2008, there have been major upheavals in the RV industry and companies have come and gone, merged, bought out and disappeared, you name it, and the RV appliance and accessory business is no exception, filtering down to two major companies acquiring all of the small manufacturers of the past.
Charles