Mothers nowadays are getting stressed over choosing a birthday theme. Others who aren't so into party planning would probably wonder what the fuss is about. They don't know that the first birthday decorations, the invitations and other stationery, the cake and whatever else will be given as game prizes and souvenir CAN depend greatly on the theme.
I say CAN because it's really up to the hosts how far they want to take a theme.
Take for example my son's first birthday party, which was Harry Potter inspired. I edited Harry Potter film posters and turned them into Invites. I embraced Halloween to make the theme more expansive and invited kiddie guests to come in costume. I had lots of candy to give away and a dessert bar (Hogsmeade was in mind). I had a basic magic act but chose a bubble show for the main event. I had badges made and a Gryffindor cloak made for my son. And we all had witches hats. And yes, I made Daily Prophet newspapers and made up stories about my son.
I only got balloons in Gryffindor colors to decorate our venue. Some would have tarps and floats and streamers and standees too. But if you really don't want to stress over so many elements, keep the theme simple. Go for generic things like animals/jungle and fairies/princess themes. Or go for the really popular ones like Disney and Looney Tunes.
And likewhat I said, make Divisoria your friend.