Yes. And no. It depends on which more specific question you are asking.

So-called "Vulgar Latin" was indeed a spoken language, no question about it. There is historical evidence as well as the evidence shown by the modern languages today (that they come from a common ancestor).

Classical Latin however was not a spoken language. As you read it, it is a highly stylistic version of Latin used as a literary language. Some more formal or poetic speakers may have presented themselves in a manner similar to that but it would be like speaking formally/stylistically today, not average daily language.

As for "complexity", no, it is not more grammatically complex than various spoken languages. It is simply different from your expectations and probably simpler in some other ways you might not have noticed such as lacking articles (the, a). So stylistically, no, Latin never was used quite like what you see written. But grammatically, more or less, yes, people did speak in that "complex" (=different) way, and speakers of many languages still do today (for whatever specific grammatical feature you want to pick or, however you want to count them, about the same "number" of such features too). Try Russian for example if you find the cases confusing. Or some Australian languages with even more flexible word order (which can be also used stylistically but also naturally in many ways). Latin is not an outlier grammatically.

It might not look quite like English but yes you can translate that. I'm not sure what you mean. Latin was spoken, although not exactly in the style it was written.

There are various ways, depending on way you want to emphasize. I'm not a Latin translator. Why not ask on a lark translation forum? I don't understand how this relates to whether Latin really existed or not...

I don't know, perhaps you could paraphrase that as "There are never heroes in the oblivion." and translate as "Heroes oblivioni numquam dantur.".
How can somebody think Latin doesn't exist, I have no idea. I mean, you can read countless pages of text on it, it was described by the grammarians in every detail, you can hear it spoken today…

Though, I should give you some credit, it's interesting that you noticed that it often takes a bit of thought to gramatically say something sensical, but it's easy to say something completely nonsensical. You need to paraphrase a bit to say "it's (not) forgotten" in Latin, yet you can easily say something like "Have forgotten!", as "Oblitus sis!" Worse, for some verbs, you could even make a morphological construction with the same meaning. Namely, the past imperative existed for the defective verbs. Its ending was -to, as in "memento" (remember). So, for instance, you could say *dixito, and that would have meant "Have said!". That's so counter-intuitive, but clearly true.

Heroes oblivioni numquam dantur.

"Heroes never give themselves to oblivion."? I don't think that has the same meaning as "Heroes are never forgotten.".

How can somebody think Latin doesn't exist, I have no idea. I mean, you can read countless pages of text on it, it was described by the grammarians in every detail, you can hear it spoken today…

So, where is all that evidence? How about this: "In Dragonland, they speak a language called Fifteeny. And it's a well-known thing there. You can read countless pages of text written on it. And they have linguists who have described that language in the biggest possible detail. If you don't believe me, go to Dragonland and hear for yourself." Have I convinced you?

Have I convinced you?

No, in fact, you've given me much less reason to take your comments here seriously. Making things up is different from widely used scientific methods, and in this case direct historical evidence.

If you have something to contribute that is on topic and serious, please do. If not, please don't post just to be argumentative.

You're welcome to believe whatever you want (dragon language was spoken in Rome, we never landed on the moon, the earth is flat), but there is literally documentation of Latin being spoken in Rome. There are some complicated details (already discussed) like stylistic questions, which could lead to a relevant and interesting conversation. But being 'skeptical' to this degree is nonsensical. There's evidence, and if you simply ignore it, there's nothing more to discuss.