Should I upgrade?

Hi Reddit! I have just recently (a couple months ago) gotten in to photography, and I am primarily interested in nature photography and astrophotography. I've been using a very old Nikon D70 with just one lens (I think it's 18-55mm). I've been studying a lot online and find it very interesting, so I'm confident I'll keep doing photography, and that it's something I won't regret putting money into. My question is, should I upgrade my Nikon D70 to something newer and stretch my budget for the camera and lenses? Or, should I keep the D70 and buy lenses for that? If so, can the D70 use newer Nikon lenses? Thanks!

Edit: the lens is actually 18-70mm