In about half of the svg examples I see on the internet, the code is wrapped in plain simple <svg></svg> tags.
In the other half, the svg tags have lots of complicated attributes like this:
<svg
xmlns="http://www.w3.org/2000/svg"
version="1.1"
xmlns:xlink="http://www.w3.org/1999/xlink">
My question is: is it ok to use the simple svg tags? I've tried playing around with the complicated ones, and everything works fine at my end if I don't include them.
All user agents (browsers) ignore the version attribute, so you can always drop that.
If you embed your SVG inline in a HTML page and serve that page as text/html then xmlns attributes are not required. Embedding SVG inline in HTML documents is a fairly recent innovation that came along as part of HTML5.
If however you serve your page as image/svg+xml or application/xhtml+xml or any other MIME type that causes the user agent to use an XML parser then the xmlns attributes are required. This was the only way to do things until recently so there is a lot of content served like this.