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I'm a beginner with Japanese and have been practising katakana more recently and in doing so, I noticed that many—maybe most—times, the reason something is written in katakana is because it is derived from English. Some katakana words are also derivatives of other languages (e.g. "アルバイト").
However, sometimes Japanese words are written in katakana despite their being originally Japanese.
How can I as a beginner distinguish between these different types of katakana?
Katakana has many functions. To check whether you are dealing with a Japanese word (where katakana has been used for emphasis, or in a scientific context, or...) or a word that is a loanword from a foreign (often Western) language, it suffices to check an ordinary monolingual dictionary, for example 大辞泉 via https://kotobank.jp/.
You don't need to be able to read the whole Japanese definition as the etymology of loanwords is listed at the beginning and in the Latin alphabet so you can't miss it. For example,
アルバイト（〈ドイツ〉Arbeit）
If you are dealing with a native Japanese word, it is usually listed with ひらがな or 漢字 (probably with exceptions). For example, ダメ would be listed as
だ‐め【駄目】
and the katakana here are for emphasis/slangyness,
There are also slang words like ググる (from グーグル Google), some of which have become standard (like サボる). For more on this take a look at Are there words which consist of katakana and hiragana letters together?
