As always with sticking things into categories, there is no clear answer. You can choose yourself whether you want to consider it butter or not.
Milk, cream and butter all lie on a spectrum, with milk having ~4% fat, and purest butter having as little water as possible and being almost all fat with only a little bit of other stuff (protein, sugar and water). With every drop of whey you squeeze out of your product, it gets a tiny bit less like milk and a tiny bit more like butter.
The "natural" (folksonomy) categorization is the functional one. Milk is good for drinking straight, cream is good for whipping and for making somewhat-thick sauces, and butter is good for use as a fat for frying, or for producing certain things like shortbread crusts and cookies. So if you are interested in this kind of use, you can simply test what your product does better - does it perform well at frying and badly at whipping, or the other way round - and then attach the label consistent with this usage.
There is also the legal classification, but I doubt that it will help you much. It requires cream to be at least 30%, double cream at least 48%, and butter at least 83% fat. From the appearance and from your description, it seems that your product is somewhere between the 48% and 83% numbers, and not especially close to either one. So it seems to fall into the no-man's-land which doesn't legally exist.
If neither classification is helpful for you - e.g. if you just want to use it as a bread spread and don't care about it behaving either like cream or like butter, or if you want to use it as in a recipe as a substitute for mascarpone or clotted cream - then your question has no correct answer. You can call it either cream or butter, or something else you fancy. In any case, you will know what you use it for. Other people's reaction will mostly be a surprise (and sometimes rejection) no matter what you call it, since they will not have handled this kind of product before and it will differ from their set expectations of what either cream or butter is.