I need help with a spring cookout menu for @ 50 people. Help!

Paella. Make one with shrimp, chicken, sausage, and one vegetarian. Serve with Spanish potato tortillas, sangria, sherry aperitifs, and a big salad. Dessert? Ice cream.

Does everybody love corn on the cob? Shuck the corn, cut the cobs in half cross-wise, parboil them for 4 minutes, then grill them a little. Brush them with melted butter with lime or lemon juice in it. The cobs can be kept warm in the oven, wrapped in foil.

You can always do a few really creative cheese/charcuterie/fruit/nuts/condiments/ veggie boards. For 50 people, 2 large or 3 medium boards will suffice. Look at this site for inspiration: https://www.cheesemonsterdc.com/

I agree with pulled pork with Asian inspired flavors of Chinese 5 spice, using lettuce wraps, hoisin and all the sides. Can make a huge amount with low time cost. Can be baked several hours in the oven with little oversight. Williams Sonoma has excellent Chinese 5 spice in their shop

Pulled pork...roast it in oven, pull it and place in big aluminum pan on grill, add barbecue sauce. Baked beans can be made day ahead. They are great cold. A variety of grilled sausages, green peppers and onions. Mixed bean salad (I have one under my profile that is great and make ahead).
Basket of Hawaiian and small rolls. Fruit skewers pineapple chunks, oranges, grapes sprinkled with coconut. Before making food place measure fridge space by placing the empty containets in your fridge that you are going use. This has saved me many headaches.
Dessert a couple 9 x 12 pans of different brownies. Cut with a plastic knife, trust me it works the best! Good luck! BB

The easiest way to elevate the typical American BBQ/picnic is to introduce seafood, especially shellfish.

There are plentiful ways to go about this but you will need to assess your budget and how much time/effort/manpower you (and any helpers you enlist) want to put into it before the event and during the event.

Tacos are a crowd favorite at my regular football tailgate. I usually grill carne asada, a buddy grills fish.

If you grill something like portobello mushrooms, you can check off the boxes next to vegan, vegetarian, gluten free.

I like tacos at tailgates because they are self-service which makes the labor aspect relatively easy. I just grill meat and some tortillas. Most people around here (SF Bay Area) understand how to assemble a taco.

Other options are ready-to-eat dishes like chili or gumbo.

You can also do a "fancier" meat like grilled ribs or something like pork tenderloins, pork loin roasts, tri-tip or other roast beef.

Naturally, chicken is an easy and affordable option.

Concerning labor, that's something no one here can advise you since we don't know if you have any helpers or not.

Let's use shrimp as an example.

If you do something like kebobs, there's a fair amount of prep work, especially if you want to include things like bell peppers, green onions, mushrooms, etc. to make the kebobs prettier. The presentation is great, but the labor increases.

If you choose to grill or pan fry the shrimp, the prep may be little more than dumping the shrimp, some marinade (olive oil, lemon juice, fresh herbs, chopped garlic) into gallon ziplocks and shaking.

Heck, we usually do a whole roasted pig once a year at our football tailgate. I've seen other tailgates roast whole pigs, so it's not something totally uncommon.

Is it too extravagant or labor-intensive for a 50th birthday? Your call.

Best of luck.

So I don't usually post my own recipes here since it feels a little...icky, but this is hands down my favorite outdoor go-to feed a crowd recipe. It stands up great over a lengthy amount of time and it's vegetarian and can serve as a main for non-meat eaters. https://food52.com/recipes/56226-pearl-couscous-chicken-salad-with-roasted-asparagus-and-herbs

My neighborhood has had great success with a do it yourself burrito bar: warming trays filled with tortillas, shredded chicken filling, shredded beef and bean fillings. Then sides of cheese, sour cream, cilantro. Start with chips and dips and end with a tres leches cake (easy to buy in our area, but also relatively easy to make). Enjoy

Depending on purveyors (what's available and good), your equipment, tastes of your group and your grilling/smoking skills, make a spread of all surf, all turf or a mixture. Clam bake, roast salmon or trout, large cuts of lamb, beef or ham. Side dishes traditional & to suit the mains.
Happy birthday to the guest of honor!

I love doing kebabs for a crowd. You can do a variety of meat and veg to satisfy everyone. Do a recipe search for "kebabs" on this site for some great recipes.