I don’t think “I started something a few months ago and I’m really good” at anything requires one to be an AO to question what “good” means.
Yes, an application that simply says “I’m really good at X” with no supporting evidence will be looked at skeptically. Because others with the same statement will likely have examples, courses, awards, etc.
You can certainly say “I’m very passionate about X” and indicate the time invested. There’s no requirement to be super great at something to be very interested in it. AOs want to know what makes you tick - what interests you, where your passion lies, etc. These activities may result in tangible recognition, but it’s certainly not required.