Knitting is a craft that requires a great deal of skill and coordination. It takes a lot of fine motor control, mental focus, patience, and perseverance to be able to complete any larger projects. Don't be discouraged if you find yourself lacking in any of these areas. If you're having trouble with the US 15 needles, try using a 5mm or 6mm needle instead.
Bamboo needles are a great choice for beginners as they are less slippery than steel needles and have more surface strength, making it less likely for stitches to fall off. Even very young children can learn to knit, depending on their manual dexterity and hand-eye coordination. Some may be ready to start at the age of five, while others may not be ready until they are around ten years old. I know from personal experience that it can take hours of practice and watching tutorials before you start to make any progress.
If you find that your first row is too tight, try putting two needles together and then pulling one out before you start knitting. When I first started knitting, I had a tendency to make my stitches too tight, especially when it came to fused stitches. There are some common mistakes that new knitters make that can easily be avoided. When knitting, it's important to remember to relax and not rush through the process.
It can be tempting to want to finish quickly or move on to something else, but it's important to take your time and enjoy the process. I've also learned that the jersey stitch is made by alternating between the backhand and point stitches, while the garter stitch is all point stitches. It's important not to pull too hard when making your stitches as this will result in a drooping stitch that will hang off the side of your fabric and eventually fray. When I hear people talk about how soothing and calming knitting can be, I'm reminded of how it can help reduce stress hormones, prevent addiction, and even potentially prevent low-level memory loss.
It's difficult to say which craft uses more yarn - knitting or crocheting - as there are many variables to consider.