I take a bit different view of that than army judge does. Rather than flat out saying you have no claim, my answer is that you might have a good claim against the seller.
Nebraska Revised Statutes (NRS) section 76-2120 is the state's law that requires certain disclosures by sellers of residential real estate. That law requires disclosure of, among other things, "any defects that materially affect the value of the real property or improvements." The basement flooding problem would certainly fall in that category. The seller had to provide to you a mandatory real estate disclosure form issued by the Nebraska Real Estate Commission. That form expressly asks for disclosure of this very problem if the seller knows of it. The Nebraska statute gives you a right to sue for damages when the seller does not comply with the disclosure law. So if the seller failed to give the disclosures or lied in the disclosures, you'd have a good claim to sue for damages. You must sue within one year of taking possession of the property to make use of this statute.
So did the seller give you that disclosure form? If so, how the did the seller answer the question "Has there been water intrusion in the basement or crawl space?" If the seller answered no or left it blank you may have a good claim here. If the water intrusion is as obvious as you say, it would ordinarily be easy to prove the seller lied when the seller is the one who lived in the home because there would be no way the seller didn't know about it. But when the seller is a landlord who didn't live in the place that provides the seller the opportunity to claim that he/she had no idea of the problem because he/she wasn't ever in there when it rained. So to make the case here you may need to contact the last tenant to find out if the tenant ever told the landlord about it. If the tenant did tell the landlord and you can get the tenant to testify to that, that may be all you need.
That depends on what assets and income he has that you may attach to collect. I have no idea what he's got, so I can't help you on that one.