I started with the ukelele.  That's a 'concert' size one to the left, but I have ones of varying sizes, including a tiny one (called a sopranino or pocket uke) and an 8-string tenor uke.  I also have a small vintage wooden banjolele.  And the largest is a four-string Tenor Banjo.  On this website and my youtube channel, you can find examples of me playing various ones.

Ukes are often disparaged as toys.  They aren't.  Neither are they small guitars - ukes share a common ancestor (the lute), and look similar, but some of the techniques and possibilities are different, and the tone is different.  Like most instruments, they have their strengths and weaknesses, limitations and specific qualities.  But they are very flexible, mainly dependant on how they are played.  Neither are they particularly 'happy' instruments - they can play a wide range of songs to suit any mood or occasion - music should elicit an emotional response, but sometimes that might be tears.  But, most of the songs I do are designed to cheer up or encourage.

Ukes are fairly easy to start with - a beginner can do a few functional strums to a tune in a few days, and I would encourage anyone to have a go.  To find out what you can buy, look here: https://www.gotaukulele.com

Of course, it takes quite a few years of playing to get to the level I am, and I am still learning (anything worth doing needs to be worked at.)