The so-called "emptiness" refers to the "emptiness of nature", and "existence" refers to "dependent origination". My teacher, Shakyamuni Buddha, taught the Dharma throughout his life from two aspects: He talked about "Dependent Origination" based on "Nature is Emptiness"; He talked about "Nature is Emptiness" based on "Dependent Origination". It’s nothing more than these two. But these two kinds can evolve into tens of thousands, countless species. Our country's Lao Tzu said in his Tao Te Ching that "Tao gives birth to one, one gives birth to two, two gives birth to three, and three gives birth to all things." This Tao has a bit of what we call "empty nature" here.
As mentioned by the poster, "Bodhisattvas, Arhats, Buddhas, gods, ghosts, etc. are all their appearances. The reason why they manifest this appearance is because their karma is different and what they create is different. But the Buddha said that although the appearance of all sentient beings is different, all sentient beings have the true nature of the Tathagata. What is the true nature of the Tathagata? Once this enlightened nature is lost, it will be lost. External objects are attracted by the realm, and there are differences, likes and dislikes, people and me, so good, they start to create karma, and the karma is caused by the six paths of reincarnation. With the six paths of reincarnation, there are gods, humans, asuras, animals, Hungry ghosts and hell are just these six realms. Buddhas and Bodhisattvas are saints who have transcended the three realms. They are not subject to the six realms. When they are enlightened, they no longer suffer from the "staged life and death" in the three realms.
The third question. "Why do idols exist? Are they created by later generations?" What do you mean by this idol? The original meaning of idols is: puppets, or images made of clay that we see in various sects now. All kinds of images are nothing more than "idols". For Buddhists, Buddha images are just a symbol. They are manifestations of Buddhas and Bodhisattvas. They are very solemn and special. They are for people to see. When someone sees it, , according to that, its image is shaped, which is what we see in the temple now. However, the Dharma body of the Buddha and Bodhisattva, please note, is formless and formless, and this Dharma body is the root of the infinite world. Does the body only exist for Buddhas and Bodhisattvas? No. Everyone has it, so why don’t we ordinary people have their own troubles to cover them up? Our human troubles cover us up, and this human body appears. There is no way, and we don't know it yet, so it is like this. We can't renounce. Let's stay in the human world. Want to renounce? Learn Buddhism and teach you how to renounce.
I think I can only say these words to people who are destined to be together. This is the general explanation of your question. If you still want to know more about it, we can communicate in private.
Amitabha!