Not really, you're making an offensive statement about someone being on a particular side because of some stereotype or another about people who feel a certain way about one thing would feel a certain way about another. You need to give content as to why not agreeing with certain types of marriages means you're against all types of marriages, which makes no sense whatsoever.
At any rate, I believe the law is that children younger than the age of 18 are allowed to marry as long as the parents give consent. I personally don't really want to think about marriage until I'm at least 25. It seems like something that would be better of waiting for. Marriage means that you're going to devote your entire life to one person, you want to make sure it's the right decision. I guess I'm on the line for this one, I think people should be able to make their own decisions, but with divorce rates as high as they are, it's just clear people need to know what they really want before making such a commitment.
Marriage is between two people. It's really a definition of love that we as humans came up with, to force that idea onto animals would be about as bad as trying to change someone's religion. We can't communicate with animals to even try to convince them our ideals are beneficial in whatever ways. As @Mailbox_Bomber put it, it doesn't matter what you get off to, but animals can't consent to marriage, it's just something they can't possibly know about.
As for objects, that's weird, and really not the point of marriage. Again, marriage is between two people, to commit to an object is really just pointless, it accomplishes nothing for you in any way. You can love it all you want but to marry it is just completely defeating the purpose.
As for polygamy, as long as all parties consent to it. Again it's a sticky situation in terms of if everyone really believes that it's the right decision, but they should be able to make that choice if they so desire. I personally don't see it working out very well for the most part, but I wouldn't be surprised if it did.