Spanish has verb endings for I, you, he/she, we, you all, and they for a simple reason: Spanish also allows “bare verbs” or sentences without explicit subjects. For example, you know that both yo hablo and hablo both mean ‘I speak’ and that both are grammatical. They may not be used in the same contexts, but they are both grammatical. There is a direct relationship, then, between verb endings in Spanish and the ability of Spanish to have sentences without subjects. The verb endings “take the place” of subject pronouns such as I, you, he/she, and so on.
This is quite different from English and French, for example. In English, only I speak is grammatical: speak, to mean the same thing, is simply not possible. And what does English lack? Verb endings. This is what’s great about languages; they tend to balance themselves. If a language has X, is probably allows Y. If a language doesn’t have X, it probably doesn’t allow Y.
So, how do you get verb endings into your mind/brain? As you’ve heard from us before, after lots and lots of exposure to verbs in context. You can practice verb endings all you want, but only by hearing hablo, tomo, como, tengo, and other verbs in context over and over do they make their way into your language system. This is one reason why your on-line activities are all about hearing and reading language in context.