... The US is thrown aside as a possible new world power with defeat at the hands at such a weary nation as Spain as of this time. ...
The US did not halt its conquest of north America because it lost a very early campaign. The common reaction of the US to a defeat has been to replace the leaders and work at it from another direction. there are exception, but that is the most common. The Spanish American War war part of a larger US expansion of influence to the south that had been going on for decades.
The probable result would be other European nations attempting to shut out US trade interests, with the US learning from its failure against Spain and crafting more effective counters. A better Navy, better Army, better political preparation, better industrial mobilization for wars would have emerged from the defeat. Much of that emerged from the victory vs Spain, and improvements have emerged from about every other US defeat. We have had our share and there is no reason to think this one would be different.