That's not knowledge and they're truths only in name, it's philosophy.

Ancient belief, not "knowledge" or "truth".

The first noble truth posits that dukkha (suffering) is a characteristic of existence in the realm of rebirth. The second, third and fourth noble truths posit that escape from dukkha (and therefore escape from the cycle of death and rebirth) is possible. "Life is suffering" is a shallow misinterpretation of Buddhist theology; Buddhists believe that all suffering has an identifiable cause and a known remedy.

Just because the Buddha said it, doesn't mean it's right. My life is many things as well as suffering. It is no more suffering than it is joy or peace. Why emphasise suffering specifically?

Another mystical text calls life the ultimate rohrschach test. You're not making (logical) arguments but rather you're showing your hand.

That is a misreading of what was said. Others have commented on it before. Life is unsatisfactory is closer to what Buddha said. He took great pains to separate physical needs from spiritual suffering. His eight fold path as a way to achieve nirvana is a solution for one of those problems. It does not put food on the table.