1. The question of whether concepts exist in the absence of a human mind to imagine them. This is still debated in philosophy. I'm not an expert, so I won't make a claim about this, but I will point out that if it was easy to resolve, it probably wouldn't be a field of active debate after 2000+ years.

2. The question of whether it is necessary that _something_ physically must exist. This I do make a strong claim on: it is not necessary that something physically exist. There is no law that forces objects to exist. We find ourselves in a universe where objects do exist. This is not required. It just happens to be the case.

Side-note: I find the response "Nope :)" to be kindof condescending. I realize English may be a second language to you, so maybe you don't feel the subtle jab in that -- no worries if so, I'm sure I make the same mistakes in other languages all the time. Smiley faces are definitely allowed online, but in general I'd say to use them when making a joke or when acknowledging your own mistake.

Edit: In case somebody is curious, "the question of whether concepts exist in the absence of a human mind to imagine them" is debated at least since plato's time. I believe these concepts-that-exist-without-humans are sometimes called Platonic Forms. They are good for a wikipedia binge!