What POS is "welcome" in "welcome to x"?

In the phrases:

"welcome home"

"welcome to Jurassic Park"

I always assumed "welcome" was a verb here, and the structure was a shortened form of:

"(I) welcome (you) home"

"(we) welcome (you all) to Jurassic Park"

In learning Spanish, I started trying to conjugate "bienvenido" like a verb but it turns out it’s ONLY an adjective. So in Spanish, the phrases are:

"(you are) welcome home"

"(you all are) welcome to Jurassic Park"

If I think of these sentences in English, I believe they use "welcome" correctly but the structure seems odd to me.

So in English, in these phrases, what is "welcome" short for and/or what POS is "welcome"? I tried thinking of a definitive example sentence but nothing’s coming to mind.

Edit: Maybe "welcome, everyone" shows it’s an adj?