In team sports, a common thing that happens is people get 'set' in a certain position. This typically happens early on: when you first try the sport, join a team, and get put in a position for your first game.
There are of course traits that dispose one more naturally to certain positions, but the selection process is typically pretty ad-hoc - as in driven more than anything by what positions the team happens to be lacking right now.
This initial selection, ad-hoc though it obviously is, is incredibly sticky. Why?
Some part of it must be practical - once selected for the position you train and play in it and specialise in its skills. Once on that trajectory it's increasingly hard to get off it and re-specialise later. People stick with things they're good at.
But another factor, and I suspect the dominant one, is sociological. Almost from the moment you are given a position in a team, certainly after playing in it for a handful of games, you receive social validation that you belong there. When you talk about yourself in relation to the team or the sport, you will find yourself naturally declaring that you 'are' that position.
Both these factors, skills and sociology together, make that first position you're selected for incredibly sticky. Usually as long as people play the sport they'll gravitate towards it.
What's curious however, and why I think the latter is dominant, is that the position often also commutes across different sports.
If your model is that skills are dominant in selection for a position, this shouldn't be true. Sure there are some commutable tactical skills, but come on -- when you start a new sport with a radically different form, stick-based Vs foot-based say, you really should be assessing from scratch which position you'd be best in based your developing skills in that form, right?
But instead, because you come in with low skill, you fall back on the comfort of the social validation of the position in the other sport. And thus the sociological element of that first ever ad-hoc pick follows you throughout your entire sporting life. Once a defender, always a defender.
Unless you are, by lucky coincidence, actually happy in that position, you should actively reject this default! Swimming against the sociological current is hard, but possible. Good times to do it are when you change teams, or sports. But really you can and should do it at any time, if you'd now prefer to play a different position than the one you were originally selected for, and you genuinely have the base skills to perform well there. Step up and offer to play there! You don't need anyone's validation but your own.
The same things hold in your career. There your position, aka role, is just whatever categorisation label has been assigned to you within your organisation. There is nothing inherently bad about this - in fact it's absolutely necessary for a team to function.
But you must internalise that you perform in the position, exercising a certain subset of your skills to do so, for the benefit of that team in that span of time. It's not that you are the position. The position's necessary skills are not a superset of your current and possible future skills.
Let's pick some concrete examples here from software. In software there are certain sociologically agreed-upon role categories like 'Frontend Engineer', 'Backend Engineer', 'SRE', etc. If you start with one of these job titles, don't accept that you're now unavoidably on a track to 'be' that position for a long time, and don't think of yourself or desribe yourself that way.
You can (and probably should) perform in any and all of these positions - and many others besides - over the span of your career. These titles draw sociological boxes around skillsets that don't exist in practice. They're just an organisational convenience. If you have the requisite skills to perform well in any of these positions, you can do all of them -- even all together.
In particular, if you are early in your career, understand that your 'selection' for a certain job title (or introductory focus if you have some general job title like Graduate Software Engineer) was likely as ad-hoc as the sport example above - driven purely by the needs of that team at that time - and having very little to do with your skills or intrinsic talents.
Language matters here. When you talk to people about your career, lean away from stating that you are or were any particular position. You weren't -- instead you simply 'performed in' or 'worked as' that position, for some concrete business need, with some outcomes, for some time period. You could obviously do a similar thing again, or, you could perform in a different position, lean more on other skills, and achieve other types of outcomes.