The Verdict: Clear Path
You are very likely Colombian by birth, because a parent was Colombian when you were born. What makes it official is registering your birth in the Colombian civil registry, which you can do at any age.
Article 96 of the Constitution makes the child of a Colombian father or mother, born abroad, Colombian by birth once the child is registered at a Colombian consulate or settles in Colombia. There is no age limit and no residence requirement: an adult can register their own birth. Colombia allows dual nationality, so you keep the nationality you already have.
What to do now: book a birth registration (registro civil de nacimiento) at the Colombian consulate that covers where you live, or at a registry office or notary in Colombia. Bring your foreign birth certificate, apostilled and translated into Spanish, and proof that your parent is Colombian: their Colombian identity card (cédula) or their own Colombian birth registration. Your parent does not have to be alive, but their Colombian documents are needed.
If you cannot get an apostilled birth certificate without unreasonable difficulty, the registry can accept two witnesses who know the facts of your birth instead. Once registered, you can apply for a Colombian identity card and passport.
If your parent became Colombian by naturalisation, this works only if you were born after they were naturalised.