Sweden? I guess you haven't played it for quite some time. Denmark was buffed (some more dev), meanwhile the hansa was split and can't support your independance anymore. Novgorod hates you, and Poland is landlocked and can't help you. Your only chances are the teutonics (very reliable), Lithuania (if Poland refuses the PU) and England (~20% of the time). You need to restart many times to make sure you can befriend at the very least England or Lithuania.Other than the Ottomans I always find Sweden to be a good starter nation in any Paradox game. EU 4 included. First of all they have great national ideas. They have room to expand if you choose to. Denmark, Norway, Northern Germany, and the Baltic nations are best. If played right can make the Baltic a Swedish lake. They can if played right form Scandinavia. They are easy to defend if a war in Europe goes badly so long as you maintain a decent navy. Only bad things are that Sweden starts out in a personal union with Denmark so you have to fight a war to break it, and compared to most majors Sweden has low manpower. The manpower problem can be remedied by fighting your wars smartly and having good allies.
Not very beginner-friendly...