Yes, I would expect that with the level increase not only the items will look cooler, but they will be also stronger and might require more or better resources.
The professions however do have different purposes. Your Animal Tamer might be able to turn wild animals into domestic ones. So let’s assume you will have to create a “leash” to promote your basic setter to an animal tamer. Over time he gains experience and will be able to tame not only wild chickens, but a (not existing) cow or finally even a mammoth. Maybe this animals can be used by your other professions, e.g… the chickens by the farmer to create food. Now, you want to use them for fighting, e.g. to turn your mammoth into a “war mammoth”. This will require a new profession - the beast master. A beast master might require a tool, too. This time the whip. So you will have to create a whip first. Second you will need an animal tamer who can be upgraded to a beast master (maybe you can just upgrade a basic worker). Now the beast master will start also with level 1, so he can turn your rabbit into a killer rabbit. For the mammoth he needs some time and experience, before he can turn it into a war mammoth.
To stay with this example… feeding a rabbit might only require a base resource, like carrots. Feeding a mammoth might require something more sophisticated, like a special plant your farmers are only able to grow once they have reached level 5. Basically this can become as complex as Radiant wants.
I have just made up this example, but I hope it makes it a bit more visual how this could work. 100% for sure we will be once the Beta is out.