Is it normal that i imagine giant animals crushing things?

Sorry for capitalized words, I am so ashamed.

I always liked to draw animals, NEVER to have sex with them.

At the age of 13-4? (don't remember the first time) I begun masturbating about animal cartoon characters stepping on things/people/me/and so on.

I hate it, feel it shameful, and I feel so frustrated...

Please, I'm NOT zoophile.
Many of you won't believe me, but there is actually something called "microphilia", that looks very similiar to this.

The difference is that in my case, the animals just do it, like they even don't see me (there are cases in which they also talk to me before), and I don't really like these things, so why would I imagine it?

The weirdest thing is that I sometimes feel the need to search for pictures (or simply cartoon characters).
I noted that there are plenty of websites about this like the "Micro/Macro" pages in furaffinity.net (choose "Browse" and select "Fetish speciality > Macro/Micro" in the "Type:" box)

But... why animals? why this topic? I just like them, and never had previous experiences with them, I DON'T seriously want to have sex with ANY, and NEVER had weird thoughts except this...

I'm 18 years old