Modern society has a bit of a prejudice against putting people into categories and with excellent reason. Modern people are no less prone to categorizing each other. This is also with good' reasons.
Problems arise when outsiders create a class and put you into it. When that happens the class is defined as a "them", people who are different from the categorizers, separated, unwelcome. Defining your own category and claiming it as an identity is less problematic. Then you have created an "us", people who are similar to each other, joined together, welcome. Except possibly for the "them" who are not "us". Unwelcoming categories are a risk whenever there are any categories besides "all of us".
But risks accompany all opportunities and the use of categories is not to be dismissed.
In recent years I have categorized myself as prosopagnostic. The advantage of this new category is that with a single word I group a constellation of experiences and interactions which I can think about together or communicate to another person. Instead of itemizing a variety of disparate symptoms I can refer a confused acquaintance to Wikipedia or to the National Institute of Neurological Disorders and Stroke or to the Prosopagnosia Research Center. The advantage of having this classification is realized because a number of people interested in the topic have agreed to the category and are actively working out what it means.
I also categorize myself as an introvert. In a similar way, the simple label encompases a range of experience. The advantages are somewhat reduced by the wide usage of the term. Too many people are inventing definitions for it; as Wikipedia says "both the popular understanding and current psychological usage vary". But the Wikipedia article (at least today!) goes on to provide a broadly helpful description which is more complete than an offhand remark I would make in the course of a conversation.
There would seem to be a sweet spot. Categories become less useful if they are subject to definition by a multiplicity of actors. On the other hand categories also become less helpful as they are less widely recognized. I can categorize myself as having "artistic temperament" but I find that only a subset of the population finds meaning in that phrase. I could describe myself as "Tsugan" or "pyritic" but even people who recognized the reference would have to guess what aspect I was trying to claim as being descriptive: rooted? eastern? beloved by fools?
Other people may use ethnic categories like "Menominee" or "Jamaican". Such categories imply shared experiences in food, music, celebrations, or social outlook. I may sometimes consider referring to myself as "Danish" but that isn't really definitional; my grandfather immigrated in 1890 and lost the language. What I have left of Denmark are a few disconnected stories and the knowledge of what an aebleskiver is without much confidence in how to pronounce it.
If someone decided to label me as Danish rather than German, Irish, English, or Yankee it would be an act of mythmaking. I might be allowed to do that for myself but I would be hesitent to accept such a categorization from another.